Herbicidal mixtures

ABSTRACT

PCT No. PCT/US96/05951 Sec. 371 Date Nov. 3, 1997 Sec. 102(e) Date Nov. 3, 1997 PCT Filed Apr. 29, 1996 PCT Pub. No. WO96/34528 PCT Pub. Date Nov. 7, 1996This invention relates to herbicidal mixtures of triflusulfuron methyl and glyphosate, herbicidal compositions of said mixtures, and a method for the use of said mixtures to control undesired vegetation.

This application is a 371 of PCT/US96/05951 filed Apr. 29, 1996.

FIELD OF THE INVENTION

The present invention relates to mixtures of herbicides that have asynergistic effect on weeds and which are safe to crop plants.

BACKGROUND OF THE INVENTION

The control of undesired vegetation is extremely important in achievinghigh crop efficiency. Achievement of selective control of the growth ofweeds especially in such useful crops as rice, soybeans, sugar beets,corn, potatoes, wheat, barley, tomatoes and plantation crops amongothers is very desirable. Unchecked weed growth in such useful crops cancause significant reduction in productivity and thereby result inincreased costs to the consumers. The control of undesired vegetation innoncrop areas is also important. The need for finding products thatachieve such results continues to be commercially important.

U.S. Pat. No. 5,090,993 discloses triflusulfuron methyl and describesits utility for selective weed control in sugar beets. U.S. Pat. Nos.4,315,765 and 4,405,531 disclose herbicidal salts of glyphosate. WIPOpublications WO 92/00377, WO 92/04449, WO 92/06201 and WO 92/19719 andU.S. Pat. Nos. 4,940,835, 4,971,908, 5,188,642 and 5,310,667 disclosemethods for genetically transforming sugar beets to make them resistantto glyphosate. None of these references disclose the mixtures of thisinvention.

SUMMARY OF THE INVENTION

This invention relates to mixtures of methyl 2-4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl!amino!carbonyl!amino!sulfonyl!-3-methylbenzoate(triflusulfuron methyl, Formula I) ##STR1## and agriculturally suitablesalts thereof with N-(phosphonomethyl)glycine (glyphosate, Formula II)##STR2## and agriculturally suitable salts, which have now beendiscovered to synergistically control weeds. This invention also relatesto herbicidal compositions comprising effective amounts of the aforesaidmixtures and at least one of the following: surfactant, solid or liquiddiluent. This invention also relates to a method for controllingundesired vegetation comprising applying to the locus of the vegetationherbicidally effective amounts of the aforesaid mixtures.

Agriculturally suitable salts of N-(phosphonomethyl)glycine (Formula II)include, but are not limited to, the salts described by Formula IIa##STR3## wherein R¹, R² and R³ are independently selected from the groupconsisting of --OH and --OR⁴, wherein R⁴ is a salt-forming cationselected from the group consisting of alkali metals, alkaline earthmetals, ammonium, and alkyl amrnmonium and mixtures thereof, providedthat no more than two of R¹, R² and R³ are --OR⁴ when R⁴ is ammonium oralkyl ammonium and that no more than two of R¹, R² and R³ are --OH; R⁴can also be alkyl sulfonium or alkyl sulfoxonium when R¹ and R³ are--OH. Alkyl ammonium includes mono-, di-, tri- and tetra-alkylammonium.Alkyl sulfonium means trialkylsulfonium, and alkyl sulfoxonium meanstrialkylsulfoxonium, where the alkyl groups are independently C₁ -C₃alkyl.

The mixtures of the invention preferred for enhanced activity include:

1. A herbicidal mixture comprising the sulfonylurea of Formula I and themono (isopropylammonium) salt of N-(phosphonomethyl)glycine (Formula II)having the common name glyphosate-isopropylammonium.

2. A herbicidal mixture comprising the sulfonylurea of Formula I and themono (trimethylsulfonium) salt of N-(phosphonomethyl)glycine (FormulaII) having the common name glyphosate-trimesium.

For reason of weed control spectrum and/or crop selectivity, thepreferred crops for application of the mixtures of this invention aresugar beet lines, varieties and cultivars containing at least one genethat confers tolerance to herbicides containingN-(phosphonomethyl)glycine or an agriculturally suitable salt as theactive ingredient.

DETAILS OF THE INVENTION

The Formula I sulfonylurea can be prepared as described in U.S. Pat. No.5,090,993. The synthesis involves the coupling of the N-silylsulfonamideof Formula 1 with the heterocyclic carbamate of Formula 2. ##STR4##

The mixtures of the present invention can include the sulfonylurea ofFormula I in the form of agriculturally suitable salts thereof. Thesecan be prepared in a number of ways known in the art. For example, metalsalts can be made by contacting the sulfonylurea of Formula I with asolution of an alkali or alkaline earth metal salt having a sufficientlybasic anion (e.g., hydroxide, alkoxide, carbonate or hydride).Quaternary amine salts can be made by similar techniques.

Salts of the sulfonylurea of Formula I can also be prepared by exchangeof one cation for another. Cationic exchange can be effected by directcontact of an aqueous solution of a salt of the sulfonylurea of FormulaI (e.g., alkali or quaternary amine salt) with a solution containing thecation to be exchanged. This method is most effective when the desiredsalt containing the exchanged cation is insoluble in water and can beseparated by filtration.

Exchange may also be effected by passing an aqueous solution of a saltof the sulfonylurea of Formula I (e.g., an alkali metal or quaternaryamine salt) through a column packed with a cation-exchange resincontaining the cation to be exchanged for that of the original salt andthe desired product is eluted from the column. This method isparticularly useful when the desired salt is water soluble (e.g., apotassium, sodium or calcium salt).

N-(phosphonomethyl)glycine (Formula II) and its agriculturally suitablesalts, including those of Formula IIa, can be prepared by methodsdescribed in U.S. Pat. No. 4,315,765 and U.S. Pat. No. 4,405,531.

Formulation/Utility

The mixtures of the Formula I and Formula II (including Formula IIa)compounds can be formulated in a number of ways:

(a) the Formula I and Formula II compounds can be formulated separatelyand applied separately or applied simultaneously in an appropriateweight ratio, e.g., as a tank mix; or

(b) the Formula I and Formula II compounds can be formulated together inthe proper weight ratio.

Mixtures of the Formula I and Formula II compounds will generally beused in formulation with an agriculturally suitable carrier comprising aliquid or solid diluent and/or a surfactant wherein the formulation isconsistent with the physical properties of the active ingredients, modeof application and environmental factors such as soil type, moisture andtemperature. Useful formulations include liquids such as solutions(including emulsifiable concentrates), suspensions, emulsions (includingmicroemulsions and/or suspoemulsions) and the like which optionally canbe thickened into gels. Useful formulations further include solids suchas dusts, powders, granules, pellets, tablets, films, and the like whichcan be water-dispersible ("wettable") or watersoluble. Activeingredients can be (micro)encapsulated and further formed into asuspension or solid formulation; alternatively the entire formulation ofactive ingredient can be encapsulated (or "overcoated"). Encapsulationcan control or delay release of the active ingredients. Sprayableformulations can be extended in suitable media and used at spray volumesfrom about one to several hundred liters per hectare. High-strengthcompositions are primarily used as intermediates for furtherformulation.

The formulations will typically contain effective amounts of activeingredients, diluent and surfactant within the following approximateranges which add up to 100 percent by weight.

    ______________________________________                  Weight Percent                  Active                  Ingredient                          Diluent   Surfactant    ______________________________________    Water-Dispersible and                    5-90       0-94     1-15    Water-soluble    Granules, Tablets and Powders.    Suspensions, Emulsions,                    5-50      40-95     0-15    Solutions    (including Emulsifiable    Concentrates)    Dusts           1-25      70-99     0-5    Granules and Pellets                    0.01-99      5-99.99                                        0-15    High Strength Compositions                    90-99      0-10     0-2    ______________________________________

Typical solid diluents are described in Watkins, et al., Handbook ofInsecticide Dust Diluents and Carriers, 2nd Ed., Dorland Books,Caldwell, N.J. Typical liquid diluents are described in Marsden,Solvents Guide, 2nd Ed., Interscience, New York, 1950. McCutcheon'sDetergents and Emulsifiers Annual, Allured Publ. Corp., Ridgewood, N.J.,as well as Sisely and Wood, Encyclopedia of Surface Active Agents,Chemical Publ. Co., Inc., New York, 1964, list surfactants andrecommended uses. All formulations can contain minor amounts ofadditives to reduce foam, caking, corrosion, microbiological growth andthe like, or thickeners to increase viscosity.

Surfactants include, for example, polyethoxylated alcohols,polyethoxylated alkylphenols, polyethoxylated sorbitan fatty acidesters, dialkyl sulfosuccinates, alkyl sulfates, alkylbenzenesulfonates, organosilicones, N,N-dialkyltaurates, lignin sulfonates,naphthalene sulfonate formaldehyde condensates, polycarboxylates, andpolyoxyethylene/polyoxypropylene block copolymers. Solid diluentsinclude, for example, clays such as bentonite, montmorillinite,attapulgite and kaolin, starch, sugar, silica, talc, diatomaceous earth,urea, calcium carbonate, sodium carbonate and bicarbonate, and sodiumsulfate. Liquid diluents include, for example, water,N,N-dimethylformamide, dimethyl sulfoxide, N-alkylpyrrolidone, ethyleneglycol, polypropylene glycol, paraffins, alkylbenzenes,alkylnaphthalenes, oils of olive, castor, linseed, tung, sesame, corn,peanut, cotton-seed, soybean, rape-seed and coconut, fatty acid esters,ketones such as cyclohexanone, 2-heptanone, isophorone and4-hydroxy-4-methyl-2-pentanone, and alcohols such as methanol,cyclohexanol, decanol and tetrahydrofurfuryl alcohol.

Solutions, including emulsifiable concentrates, can be prepared bysimply mixing the ingredients. Chemically stabilized aqueoussulfonylurea or agriculturally suitable sulfonylurea salt dispersionsare taught in U.S. Pat. No. 4,936,900. Solution formulations ofsulfonylureas with improved chemical stability are taught in U.S. Pat.No. 4,599,412. Dusts and powders can be prepared by blending and,usually, grinding as in a hammer mill or fluid-energy mill. Suspensionsare usually prepared by wet-milling; see, for example, U.S. Pat. No.3,060,084. Granules and pellets can be prepared by spraying the activematerial upon preformed granular carriers or by agglomerationtechniques. See Browning, "Agglomeration", Chemical Engineering, Dec. 4,1967, pp 147-48, Perry's Chemical Engineer's Handbook, 4th Ed.,McGraw-Hill, New York, 1963, pages 8-57 and following, and WO 91/13546.Pellets can be prepared as described in U.S. Pat. No. 4,172,714.Water-dispersible and water-soluble granules can be prepared as taughtin U.S. Pat. No. 4,144,050, U.S. Pat. No. 3,920,442 and DE 3,246,493.Tablets can be prepared as taught in U.S. Pat. No. 5,180,587, U.S. Pat.No. 5,232,701 and U.S. Pat. No. 5,208,030. Films can be prepared astaught in GB 2,095,558 and U.S. Pat. No. 3,299,566.

For further information regarding formulation, see U.S. Pat. No.3,235,361, Col. 6, line 16 through Col. 7, line 19 and Examples 10-41;U.S. Pat. No. 3,309,192, Col. 5, line 43 through Col. 7, line 62 andExamples 8, 12, 15, 39, 41, 52, 53, 58, 132, 138-140, 162-164, 166, 167and 169-182; U.S. Pat. No. 2,891,855, Col. 3, line 66 through Col. 5,line 17 and Examples 1-4; Klingman, Weed Control as a Science, JohnWiley and Sons, Inc., New York, 1961, pp 81-96; and Hance et al., WeedControl Handbook, 8th Ed., Blackwell Scientific Publications, Oxford,1989.

In the following Examples, all percentages are by weight and allformulations are prepared in conventional ways.

    ______________________________________    Example A    High Strength Concentrate    triflusulfuron methyl  4.7%    glyphosate-isopropylammonium                           93.8%    silica aerogel         0.5%    synthetic amorphous fine silica                           1.0%.    Example B    Wettable Powder    triflusulfuron methyl  5.0%    glyphosate-trimesium   60.0%    dodecylphenol polyethylene glycol ether                           2.0%    sodium ligninsulfonate 4.0%    sodium silicoaluminate 6.0%    montmorillonite (calcined)                           23.0%.    Example C    Granule    triflusulfuron methyl  0.8%    glyphosate-isopropylammonium                           9.2%    attapulgite granules (low volatile matter,                           90.0%.    0.71/0.30 mm; U.S.S. No. 25-50 sieves)    Example D    Aqueous Solution Suspension    triflusulfuron methyl  0.1%    glyphosate-isopropylammonium                           24.9%    hydrated attapulgite   3.0%    crude calcium ligninsulfonate                           10.0%    sodium dihydrogen phosphate                           0.5%    water                  61.5%.    Example E    Extruded Pellet    triflusulfuron methyl  0.2%    glyphosate-isopropylammonium                           24.8%    anhydrous sodium sulfate                           10.0%    crude calcium ligninsulfonate                           5.0%    sodium alkylnaphthalenesulfonate                           1.0%    calcium/magnesium bentonite                           59.0%.    Example F    Wettable Powder    triflusulfuron methyl  0.1%    glyphosate-isopropylammonium                           64.9%    dodecylphenol polyethylene glycol ether                           2.0%    sodium ligninsulfonate 4.0%    sodium silicoaluminate 6.0%    montmorillonite (calcined)                           23.0%.    ______________________________________

Utility

Test results indicate that mixtures of compounds of Formula I andFormula II (including Formula IIa) are highly active postemergentherbicides, providing unexpected synergistic control of selected grassand broadleaf weeds. Because of the efficacy of the mixtures of thepresent invention in controlling weeds that commonly infest sugar beetfields, they are particularly valued for their selective tolerance bysugar beet plants containing at least one gene that confers resistanceto N-(phosphonomethyl)glycine and its agriculturally suitable salts.Sugar beet varieties, cultivars, and lines that have been "gene-altered"to confer resistance to N-(phosphonomethyl)glycine can be developed by avariety of methods used individually or in combination including:modification to increase biosynthesis of5-enolpyruvyl-3-phosphoshikimate synthase, incorporation of genesencoding 5-enolpyruvyl-3-phosphoshikimate synthase with structuremodified to reduce its inhibition by N-(phosphonomethyl)glycine, andincorporation of genes encoding enzymes to degradeN-phosphonmethylglycine, by methods known in the art, including thosedescribed in WO 92/00377, WO 92/04449, WO 92/06201 and WO 92/19719, U.S.Pat. No. 4,940,835, U.S. Pat. No. 4,971,908, U.S. Pat. No. 5,188,642 andU.S. Pat. No. 5,310,667.

In the context of this disclosure, a "line" is a group of plants ofsimilar parentage that display little or no genetic variation betweenindividuals for at least one trait. Such lines may be created by one ormore generations of self-pollination and selection, or by vegetativepropagation from a single parent, such as by tissue or cell culturetechniques. A "variety" or "cultivar" refers to an agronomicallysuperior line that has been extensively tested and is (or was) beingused for commercial production.

The Formula I and Formula II mixtures of this invention can additionallybe used in combination with other commercial herbicides, insecticides orfungicides. A mixture of one or more additional herbicides with theFormula I and Formula II mixtures of this invention may be particularlyuseful for weed control. In certain instances, combinations with otherherbicides having similar spectrum of control but a different mode ofaction will be particularly advantageous for resistance management.Examples of other herbicides as mixture partners are: barban,bromoxynil, clodinafop, chloridazon, chlorpropham, cycloate, dalapon,desmedipham, diallate, diethatyl, endothal, EPTC, fenoxaprop,fenoxaprop-P, fluazifop, ethofumesate, glufosinate, haloxyfop, lenacil,metamitron, pebulate, phenmedipham, propham, sethoxydim, TCA,tralkoxydim, trifluralin, and quizalofop.

An herbicidally effective amount of both the compounds of Formula I andFormula II will vary depending on environmental conditions, formulation,method of application, amount and type of vegetation present, etc. Theuse rate ratios of Formula I to Formula II are in general 1:8 to 1:500,with ratios of 1:15 to 1:100 preferred for most uses. In general, theFormula I compound is applied at a rate from 1 to 30 g ai/ha and FormulaII compound is applied at a rate from 125 to 1500 g ai/ha. Preferably,Formula I compound is applied at a rate from 10 to 15 g ai/ha, and theFormula II compound is applied at a rate from 250 to 1000 g ai/ha.

For synergistic control of selected weed species in sugar beet crops,the mixtures of the invention are best applied when the sugar beetplants are at about the cotyledon to two-leaf stage and the weed plantsare correspondingly young. One skilled in the art can readily determineapplication rates and ratios of herbicide of Formula I to the herbicideof Formula II as well as timing necessary for the desired level of weedcontrol and crop safety.

The Formula I sulfonylurea (Compound 1) was tested in combination withthe mono isopropylamine salt of N-(phosphonomethyl)glycine (Formula II)(Compound 2). ##STR5##

The following protocol was used for the test whose results are listed inTable 1. The data demonstrate the surprising efficacy of the Formula Iand Formula II mixtures of this invention against specific weeds. Theweed control afforded by the mixtures of this invention are not limited,however, to these species.

Test Protocol

Sugar beet crops were planted during the summer in an area of Francehaving high natural infestations of weed species such as Amaranthusretroflexus (redroot pigweed) (AMARE), Chenopodium album (commonlambsquarters) (CHEAL), and Polygonum persicaria (ladysthumb) (POLPE).Test plots were treated postemergence to the crops and weeds at thetwo-leaf stage of the sugar beet plants. Compound 1 was formulated as asingle active ingredient in 50% strength dry flowable granules. Compound2 was formulated as a high-surfactant aqueous solution containing theequivalent of 120 g/L of glyphosate acid (Formula II). Herbicides wereapplied to the test area by diluting the formulated herbicides in anaqueous solution to the appropriate concentration to deliver the desireduse rate; spray volumes of about 150 L/ha were typically used. Theprepared test solutions were then sprayed onto the test plots throughstandard T-Jet flat-fan nozzles. When applied as mixtures, Compounds 1and 2 were tank mixed. No additional adjuvants such as surfactants wereadded to the spray solution. Individual treatments were replicated threetimes at the field trial location.

Assessments of weed control were made by visual inspection about 21 daysfollowing herbicide application. A visual rating system was used basedon a percentage scale from 0 to 100%, relative to an adjacent untreatedcontrol plot or test area. On this scale 0% represents no visualdifferences relative to an untreated control, 100% represents completekill of the given crop or weed species.

Colby's equation was used to calculate the expected additive herbicidaleffect of the mixtures of Compound 1 and Compound 2. Colby's equation(Colby, S. R. "Calculating Synergistic and Antagonistic Responses ofHerbicide Combinations," Weeds, 15(1), pp 20-22 (1967)) calculates theexpected additive effect of herbicidal mixtures, and for two activeingredients is of the form:

    P.sub.a+b =P.sub.a +P.sub.b -(P.sub.a P.sub.b /100)

wherein

P_(a+b) is the percentage effect of the mixture expected from additivecontribution of the individual components,

P_(a) is the observed percentage effect of the first active ingredientat the same use rate as in the mixture, and

P_(b) is the observed percentage effect of the second active ingredientat the same use rate as in the mixture.

Table 1 represents visual assessments of control of specific weeds withCompound 1 and Compound 2 applied alone as single active ingredients,applied as a mixture of the two active ingredients of Compound 1 andCompound 2, and the expected additive effect of the herbicidal mixtureof Compound 1 and Compound 2 (Colby's equation). Different ratios ofCompound 1 to Compound 2, and different formulation types, also provideuseful weed control from the combination of the two herbicides.

                  TABLE 1*    ______________________________________    Effect of Compound 1 and Compound 2 as    Active Ingredients Alone and in Mixture    CMPD 1 CMPD 2        AMARE    CHEAL   POLPE    ______________________________________    Alone    10     0        Mean     0      0       0    15     0        Mean     10     10      10    0      250      Mean     82     46      47    0      500      Mean     93     83      67    0      1000     Mean     99     88      82    Mixtures    10     250      Mean     86     52      50                    Colby†                             82     46      47    10     500      Mean     96     85      82                    Colby    93     83      67    10     1000     Mean     99     97      96                    Colby    99     93      82    15     250      Mean     91     72      60                    Colby    84     51      52    15     500      Mean     98     85      82                    Colby    94     85      70    15     1000     Mean     100    98      98                    Colby    99     94      84    ______________________________________     *Application rates are expressed in g ai/ha. Application rates for     Compound 2 are expressed in terms of equivalent glyphosate acid (Formula     II). Data are reported as percent control.     †Colby, S. R. "Calculating Synergistic and Antagonistic Responses     of Herbicide Combinations," Weeds, 15(1), pp 20-22 (1967).

What is claimed is:
 1. A herbicidal mixture comprising synergisticherbicidally effective amounts of the compound of Formula I ##STR6##which is methyl 2-4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl!amino!-carbonyl!amino!sulfonyl!-3-methylbenzoate(triflusulfuron methyl) and agriculturally suitable salts thereofand thecompound of Formula II ##STR7## which is N-(phosphonomethyl)glycine(glyphosate) and agriculturally suitable salts thereof, wherein thecompound of Formula I and the compound of Formula II are in a ratio byweight of from 1:15 to 1:100.
 2. A mixture of claim 1 wherein thecompound of Formula II is in the form of its mono isopropylamine salt.3. A mixture of claim 1 wherein the compound of Formula II is in theform of its mono trimethylsulfonium salt.
 4. An agriculturally suitablecomposition for controlling the growth of undesired vegetationcomprising an effective amount of the herbicidal mixtures of claim 1 andat least one of the following: surfactant, solid or liquid diluent. 5.An agriculturally suitable composition for controlling the growth ofundesired vegetation comprising an effective amount of the herbicidalmixtures of claim 2 and at least one of the following: surfactant, solidor liquid diluent.
 6. An agriculturally suitable composition forcontrolling the growth of undesired vegetation comprising an effectiveamount of the herbicidal mixtures of claim 3 and at least one of thefollowing: surfactant, solid or liquid diluent.
 7. The composition ofclaim 4 wherein the undesired vegetation is the vegetation in a crop ofsugar beet plants containing at least one gene that confers resistanceto glyphosate and its agriculturally suitable salts.
 8. A method forcontrolling the growth of undesired vegetation comprising contacting thelocus to be protected with a herbicidally effective amount of thecomposition of claim
 4. 9. A method for controlling the growth ofundesired vegetation comprising contacting the locus to be protectedwith a herbicidally effective amount of the composition of claim
 5. 10.A method for controlling the growth of undesired vegetation comprisingcontacting the locus to be protected with a herbicidally effectiveamount of the composition of claim
 6. 11. The method of claim 8 whereinthe locus to be protected is a crop of sugar beet plants containing atleast one gene that confers resistance to glyphosate and itsagriculturally suitable salts.